1195777 - Add report_objects=1 to LSan options

Status: RESOLVED FIXED

(Core :: General, defect)

Description

[Jan de Mooij [:jandem]]

Attachment: Patch

I used this to track down bug 1194627. With this option enabled, LSan prints the following after the leak report:

13:19:50     INFO -  Objects leaked above:
13:19:50     INFO -  0x60600055a120 (64 bytes)

Knowing the address is extremely useful because you can then add logging to the allocation site to find out more.

Comment 1

[Andrew McCreight [:mccr8]]

That's a nice feature I didn't know about.

It seems a little odd to print out the address all the time when it is not useful without additional logging. XPCOM leak logging can also report addresses, but does not do it by default.

Also, can you show a little more context for the output, or maybe link to a log? I'm curious what comes before and after it. I'm just worried if it will interfere with our LSan report parsing.

Comment 2

[Jan de Mooij [:jandem]]

(In reply to Andrew McCreight [:mccr8] from comment #1)
> It seems a little odd to print out the address all the time when it is not
> useful without additional logging. XPCOM leak logging can also report
> addresses, but does not do it by default.

Fair enough, but we're already reporting the stack trace at the allocation site, that's a lot more information than just the address right?

> Also, can you show a little more context for the output, or maybe link to a
> log? I'm curious what comes before and after it. I'm just worried if it will
> interfere with our LSan report parsing.

Sure, here's a report (search for `leaked`):

http://ftp.mozilla.org/pub/mozilla.org/firefox/try-builds/[e-mail]-0bf12f3b1c72/try-linux64-asan/try_ubuntu64-asan_vm_test-mochitest-e10s-browser-chrome-3-bm116-tests1-linux64-build165.txt.gz

Comment 3

[Jan de Mooij [:jandem]]

(In reply to Jan de Mooij [:jandem] from comment #2)
> (In reply to Andrew McCreight [:mccr8] from comment #1)
> > It seems a little odd to print out the address all the time when it is not
> > useful without additional logging. XPCOM leak logging can also report
> > addresses, but does not do it by default.
> 
> Fair enough, but we're already reporting the stack trace at the allocation
> site, that's a lot more information than just the address right?

Oh sorry I missed the "without additional logging" part. That's a good point, though most people won't know about report_objects=1. Maybe we can print a line "Use report_objects=1 to ..." or add it to some wiki page.

Comment 4

[Andrew McCreight [:mccr8]]

Attachment: When LSan detects leaks, tell the user about the report_objects option.

That's a good idea. How does something like this look to you?

Comment 5

[Jan de Mooij [:jandem]]

Comment on attachment 8649363 [details] [diff] [review]
When LSan detects leaks, tell the user about the report_objects option.

Review of attachment 8649363 [details] [diff] [review]:
-----------------------------------------------------------------

Yep this seems fine, thanks.

It adds the same number of lines though and requires additional work when someone needs this, but I don't have a strong opinion on it :)

Comment 6

[Andrew McCreight [:mccr8]]

(In reply to Jan de Mooij [:jandem] from comment #5)
> It adds the same number of lines though and requires additional work when
> someone needs this, but I don't have a strong opinion on it :)

It adds less lines in the case where we are leaking many objects (sometimes we leak hundreds of them), though in that case there are going so many stacks it may not really matter. I'll pick this up from here and get it landed, and add something to our wiki about it. Thanks for suggesting this!

Comment 7

[Andrew McCreight [:mccr8]]

Comment on attachment 8649301 [details] [diff] [review]
Patch

I'll try my alternate approach here.

Comment 8

[Andrew McCreight [:mccr8]]

Attachment: When LSan detects leaks, tell the user about the report_objects option.

Comment 9

[Chris Manchester (limited bugmail, email directly)]

Comment on attachment 8775302 [details] [diff] [review]
When LSan detects leaks, tell the user about the report_objects option.

Review of attachment 8775302 [details] [diff] [review]:
-----------------------------------------------------------------

::: testing/mochitest/leaks.py
@@ +222,5 @@
>  
>      def process(self):
> +        if self.foundFrames:
> +            self.logger.info("TEST-INFO | LeakSanitizer | To show the addresses of leaked objects add report_objects=1 to LSAN_OPTIONS")
> +            self.logger.info("TEST-INFO | LeakSanitizer | This can be done in testing/mozbase/mozrunner/mozrunner/utils.py")

This message seems likely to bitrot, but I guess there's no harm done.

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/fcc56a97afb3
When LSan detects leaks, tell the user about the report_objects option. r=chmanchester

Comment 11

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/fcc56a97afb3